Fundamentals

The letting down of gas by valves from a high to a low pressure can produce a troublesome and, in extre cases, unbearable noise....

In the case of a liquid, this transient change in the static pressure is sometimes accompanied by a shaking of the pipe and a hammering sound—thus the name waterhammer....

When a liquid passes through a partially closed valve, the static pressure in the region of increasing velocity and in the wake of the closure member drops and may reach ...

The relationship between fractional valve opening position and relative flow through the valve is denoted as flow characteristic....

Resistance and flow coefficients are interrelated. If one coefficient is known, the other coefficients can be calculated....

The flow coefficient Cv states the flow capacity of a valve in gal (U.S.)/min of water at a temperature of 60℉ that will flow through a valve with a pressure loss of one poun...

The resistance coefficient ζ defines the friction loss attributable to a valve in a pipeline in terms of velocity head or velocity pressure, as expressed by the equations....

Compression packings are the sealing elements in stuffing boxes (see Figures 3-17 through 3-19). They consist of a soft material that is stuffed into the stuffing box and c...

Flat metallic gaskets adapt to the irregularities of the flange face by elastic and plastic deformation. To inhibit plastic deformation of the flange face, the yieldshear s...

The effectiveness of the seating and the subsequent sealing of a valve are very important factors in the selection of a valve for a specific process function....

One of the duties of most valves is to provide a fuid seal between the seat and the closure member. If the closure member is moved by a stem that penetrates into the pres...

Valve types can be dived into stop valves, vertiacl slide valves, rotary valves, flexible body, check valve and pressure relief valves....

The sealability against liquids is determined by the surface tension and the viscosity of the liquid....